Footage has emerged showing the extraordinary moment a dying great white shark tried to beach itself in Australia after biting off more than it could chew.

The mysterious death of the four-metre (13-ft) long male sparked an investigation from fisheries officials in Western Australia (WA) when it washed up on Coronation Beach this week.

Two days earlier beachgoers had filmed a shark, believed to be the same one, in clear distress as it thrashed about in the shallow water.

Concluding their investigation today, WA Department of Fisheries experts said the shark had no visible signs of injury or disease – but it did have a large Australian sea lion stuck inside its throat.

“This could explain why the shark was exhibiting such unusual behaviour in shallow waters off Coronation Beach. It is possible that the shark was trying to dislodge the blockage,” said lead scientist Dr Rory McAuley.

“Such a large object may have damaged the shark’s internal organs or impeded water flow into his gills, contributing to his death. Alternatively, the shark may have accidentally become stranded in his attempts to get rid of the obstruction.”

WA Fisheries also confirmed that the shark was a tagged specimen – as those who filmed its last moments can be heard commenting on in the video.

Dr McAuley said records showed the tag was put in place in South Australia in January this year. “Confirmation of when and where this shark was tagged demonstrates the extraordinarily mobile nature of this species,” he added.

Brad and Tash Tapper, locals from nearby Geraldton who filmed the shark, said a dog walker had first raised the alarm when his pet refused to go in the water.

Ms Tapper told the WA Today newspaper that she and her husband watched the shark swim in from around 50 metres out up close to the shore, back out and then in again for almost two hours.

She said that at one point onlookers tried to help the animal when it beached itself on a reef, but that they stopped when they quickly realised how unwell it was.